This is an anime based on a real live movie called "Zeiram". This is like a prequal. It's about a young bounty hunter named Iria. There is a starship, Karma, that has problems. Her brother Gren and his boss Bob get called out to go check on it and she goes along. It was carrying a deadly cargo. Zeiram, a superpowerful killing maching that Teddan Tippeday to use as a weapon. Gren disappears under mysterious circumstances and Bob is "killed".
After following her brothers advice and hauling ass out of the area where the Karma used to be she crash lands on a planet. Turns out the explosion didn't kill Zeiram and he crashed along with her! The authorites don't to anything when the alien starts tearing up the "Shadow Zone", a slum area on the resort planet. A cockey street urchin named Kei gives Iria a hand. Finally Zeiram is transited away and Iria gets back to Myce to find out what's going on.
Two of the street kids from the resort planet, one of which being Kei, stow away on a starship bound for Myce. Zeiram clones are on board and capture the scientist/Zeiram expert Dr. Toka. Iria is finally made a real bounty hunter and is sent to take care of business. While there she finds that her brother might have been cloned by Zeiram after he was asimillated. Now she's really pissed off and wants revenge!
The third and final volume is the climactic battle between Iria and Zeiram. A loner by nature she has headed out on her own and no one has seen her for a while. Zeiram has taken over one of the buildings in the city and is proceeding to call in reinforcements. Iria's rival/friend Fujikuro and Kei are watching this all happen. Finally Kei is sick of waiting and tries to go out alone. At last Iria shows up. Things proceed at an amazing pace until finally they are both transited to the Stardust Desert for the final showdown.
The art is very good. I think the story is exceptional and the music is the best I've ever heard since PSME. This is three OAV's long. You can find them in box sets sometimes and I heard that they are releasing all three on one DVD. This is a must see for sci-fi fans.